Underwater adhesive process

ABSTRACT

Pastes of Alpha -cyanoacrylic acid esters and insoluble fillers can be applied to surfaces submerged in water for securing thereto, in situ, a wide variety of metallic and nonmetallic substances.

United States Patent Continuation-impart of application Ser. No. 699,062, Jan. 19, 1968, Continuation-inpart of application Ser. No. 586,316, Oct.

7 10, 1966, now abandoned.

[54] UNDERWATER ADHESIVE PROCESS 1 Claim, No Drawings [52] US. Cl 156/285,

511 mu; C09j5/04 [50] FieldofSearch 106/287; 260/465.4, 41; 156/327, 331, 285

[56] References Cited UNITED STATES PATENTS 2,765,332 10/1956 Coover et a1. 260/464 2,784,127 3/1957 Joyner et al. 161/204 2,794,788 6/1957 Coover et al. 260/17 2,849,410 8/1958 Lamm 260/27 Primary ExaminerLorenz0 B. Hayes Attorneys-Charles K. Wright, Jr., William G. Gapcynski and Lawrence A. Neureither ABSTRACT: Pastes of a-cyanoacrylic acid esters and insoluble fillers can be applied to surfaces submerged in water for securing thereto, in situ, a wide variety of metallic and nonmetallic substances.

UNDERWATER ADHESIVE PROCESS CROSS-REFERENCE TO RELATED APPLICATION This is a continuation-in-part of our parent application Ser. No. 699,062 filed Jan. 19, i968, which is a continuation-inpart ofSer. No. 586,316 filed Oct. 10, 1966, now abandoned.

BACKGROUND OF THE INVENTION 1. Field ofthe Invention This invention relates to compositions capable of being applied to surfaces submerged in water to secure together a wide variety of metallic and nonmetallic solid substances, e.g. glass, aluminum, steel, stainless steel, plastics, rubber and wood. The compositions of this invention are useful for underwater repair of ships and other structures, and sealing in place underwater demolition charges and explosives. They also have health field applications, e.g., dental, such as fillings for teeth; for this purpose n-butyl-a-cyanoacrylate is the preferred monomer and calcium carbonate is the preferred filler. The invention includes the preparation and a particular application of said compositions.

2. Description of the Prior Art Adhesive compositions are generally useless for application under water, in the main, because the film of water on the sub strate surface prevents its being wetted by the adhesive'Previously known compositions either dissolve in water, float away from the surfaces to be joined or, in the case of various adhesive monomers, polymerize instantaneously on contact with water or too slowly to be of substantial utility.

SUMMARY The compositions of this invention contain, as essential ingredients, at least one liquid monomer of a class known as acyanoacrylic acid esters and at least one water-insoluble weakly alkaline to acid filler which is, effectively, inert with respect to the monomer and essentially insoluble therein. The filler is admixed with the liquid monomer to form a thickened pastelike mixture which remains integral under water and does not flow away from the site of application. Suitable pastes contain, e.g., from 2 to 4 parts by weight of monomer, from 2 to 4 parts by weight of filler and from to 0.3 part by weight of finely divided silica.

Accordingly, it is -an object of this invention to provide a composition which is an adhesive paste capable of being applied to a surface submerged in water. Another object is be provide an adhesive mixture capable of joining, in situ, two surfaces submerged in water, the surfaces being of the same or different materials. A further object is to provide an adhesive composition which will neither dissolve in water, flow away from the site of application in water, harden immediately on contact with water nor take unduly long to harden when sub merged in water. An additional object is to provide an adhesive mixture which, when applied under water, will permit a reasonable working time for underwater application and will harden substantially uniformly. A still further object is to provide an underwater adhesive which can develop high bond strengths within 1 minute after application. These and other objects, readily apparent with reference to the following description, are achieved by the subject invention.

DESCRIPTION OF THE PREFERRED EMBODIMENTS these, it is particularly advantageous to employ those wherein R is alkyl having from 4 to 8 carbon atoms, either straight or branched chain. R is, alternatively, substituted alkyl having from 1 to 10 carbon atoms. The substituents are unlimited as long as the monomers are liquid. Illustrative substituents are lower alkoxy having from I to 4 carbon atoms [ethoxyethyl-acyanoacrylate] and halo, e.g. chloro and fluoro [trifluoroisopropyl-a-cyanoacrylate (In the trifluoroisopropyl group the three fluorine atoms are bonded to the same carbon atom). In addition R can also be, e.g., cyclohexyl, phenyl or allyl. The sole restrictions on R are that the monomer must be liquid at room temperature (20 C) and atmospheric pressure and a carbon atom of R must be directly bound to the H C=C(CN)-CO-O-group. It is also essential that the acyanoacrylate be unsubstituted in the B-position. That means that the hydrogen atoms in the B-position cannot be replaced. The contemplated a-cyanoacrylates must have the structure:

without variation in this portion of the molecule.

The liquid a-cyanoacrylates are monomers prepared, e.g., according to the method disclosed by US Pat. No. 2,763,677 (hereafter: Jeremias). The precursors are either known or are available from known starting materials following published procedures. Where R is alkyl, monomers prepared according to the Jeremias procedure have purities of 98.5 percent or higher.

The pH designated for the monomer is measured by adding one gram of monomer and 0.2 gram of sodium chloride to 50 cubic centimeters of water. The mixture is then stirred and the pH checked with a standard pH meter or other laboratory indicator. It has been found that the pH is a critical factor. A range of from 2.45 to 4.! preferably from 3.0 to 4.1, permits a good homogenous mixture with inorganic fillers, such as calcium carbonate and amorphous silica. As the pH isincreased above 4.1, clumping occurs (depending upon the alkalinity of the tiller); at a pH below 3.7 homogenous pastes'are prepared, but delayed curing time results. This is advantageous for those monomers which polymerize most rapidly on contact with water. These have preferred pHs, e.g. methyl-a-cyanoacrylate (pH 2.45), ethyl-a-cyanoacrylate (pH 2.7) and propyl-acyanoacrylate (pH 2.7), below 3.7. lt has also been found that in particular aqueous media, e.g., sea water that has contamination of a type which is not readily determined, tensile strengths may be improved by reducing the pH below the range of from 3.7 to 4.1. Particular substrates, eg. HY steel, also adhere more strongly at lower pHs. Propyl-acyanoacrylate has been found to yield particularly good results (strong bonds) with HY-SO steel.

The pH is controlled, e.g., by adding sulfur dioxide to the monomer during distillation in accord with Jeremias disclosure or by adding sulfur dioxide to the monomer after distillation. In lieu of sulfur dioxide other acidic inhibitors (against anionic polymerization), such as nitric oxide, nitrous oxide, carbon dioxide, hydrogen fluoride, trichloroacetic acid and acetic anhydride, can be used to stabilize the monomer. (Carbon dioxide is recommended only for monomers wherein R has at least four carbon atoms). In combination with the acidic inhibitor a free radical inhibitor, such as hydroquinone, monomethylether of hydroquinone, picric acid and t-butylcatechol, should be concurrently employed. The monomethylether ofhydroquinone is the preferred stabilizer against free radical polymerization. Moreover, it imparts good color stability to both the monomeric a-cyanoacrylate and the polymerized product therefrom. This has critical significance in the health field. Free radical inhibition is obtained with, e.g., 10 parts of the monomethylether of hydroquinone per million parts of a-cyanoacrylic acid ester; in practice from 15 to 200 parts per million are employed.

As the number of carbon atoms in the alkyl chain of R is increased, the hydrophobicity of the monomers is increased. The methyl, ethyl and propyl esters are relatively hydrophillic and require a lower pH to make their use practical. These, as the essential monomers in the paste compositions at the above-noted preferred pHs, are effectively delivered through, e.g., a polyethylene delivery tube to a surface of, e.g., a submerged steel jig to be glued under water, a steel jig counterpart being immediately placed on said delivered paste.

Although the butyl and amyl esters are more hydrophobic than the methyl, ethyl and propyl and generally more satisfactory to use, the hexyl, heptyl and octyl-a-cyanoacrylates are most satisfactory both from the standpoint of optimum working time and resistance of the resulting adhesive bond to subsequent hydrolytic degradation. V

The amyl and hexyl homologs are preferred for underwater applications in view of their case of handling, preparation and obtainable tensile strengths. g V

The filler is insoluble weakly alkaline to acid material essentially inert with respect to the liquid a-cyanoacrylate ester monomer. Exemplary fillers are calcium carbonate, calcium sulfate dihydrate, calcium sulfate, titanium dioxide, zinc oxide, zinc hydroxide, calcium oxide, magnesium oxide, stannic oxide, stannous oxide, aluminum oxide, aluminum silicate, calcium silicate, zinc silicate, calcium aluminate, mercuric oxide, silver oxide, cuprous oxide, cupric oxide, strontium oxide, ferrous oxide, ferric oxide, zinc phosphate, calcium phosphate, aluminum phosphate, talc, barium sulfate, barium carbonate and calcium sulfate hemihydrate. These are best employed in a finely divided state so that they can most readily be admixed with the liquid monomer to form a paste. The preferred fillers are those which are neutral to weakly alkaline. Although silica does not readily mix with monomer to form a paste, it is advantageously employed in conjunction with other fillers, e.g., to control the fluidity of the paste.

The preferred fillers are either calcium carbonate alone or a mixture of calcium carbonate and amorphous silica. The preferred amorphous silica is a line colloidal size silica of 99 percent purity prepared in a rapid, high temperature flame process as a white soot and sold under the name Cab-O-Sil (trademark) by Geoffry Cabot Company. For stable pastes with chemically pure barium carbonate, the pH designated for the monomer (according to the indicated testing procedure) is .Qi sthislisihs iql s s set a bet? Although each of the above-noted fillers is inorganic and inorganic fillers are preferred, organic fillers can be used in lieu thereof. An organic filler can, but need not, be a pigment, such as carbon black, Different effects are obtained with different fillers in different concentrations. The fillers are solids other than organic polymers since the latter ordinarily are soluble in a-cyanoacrylates and therefore do not form suitable pastes. All fillers which are a) essentially inert with respect to the employed a-cyanoacrylate, b) insoluble in the employed a-cyanoacrylate, c) insoluble in water and d) form pastes with said a-cyanoacrylate are effective in forming compositions which are useful in adhering together two surfaces submerged in water. 7'

The term insoluble" is relative. Although it is said that there is no substance which is completely insoluble in water, the expression water-insoluble" is employed in technical writings and is readily understood. The expression water-insoluble" is used herein to define fillers having a water solubility (at room temperature) no greater than 1 gram/100 milliliters. For ease of handling it is well to employ filler having a solubility in water of less than 0.5 gram (g.)/l milliliters (ml.) of water or, preferably, less than 0.01 g./l00 ml. of water at room temperature.

The filler must also be essentially insoluble in the acyanoacrylate so that the adhesive composition will be in the form of a paste. By paste or pastlike is meant a dispersion in a liquid a-cyanoacrylate of solid particles of filler which is essentially insoluble therein. The paste may vary in consistency. It is preferred that the paste have only a slight tendency to flow of its own volition and yet be such that it can readily be caused to flow or spread. The paste should not be watery and should remain integral when delivered to a submerged substrate. Dispersions having the consistency of toothpaste or even more fluid are easiest to work with. The paste preferably has a density greater than thatof water.

The particle size of the filler is not critical beyond the general requirements for fillers in solid-in-liquid dispersions capable of flow The range of average particle size is ordinarily between and 300 mesh, but a much broader range is suitable for the intended purpose.

The underwater adhesive compositions are not limited to liquid-a-cyanoacrylate monomer and inorganic (or organic) fillers. It is also possible to use a liquid a-cyanoacrylate monomer having dissolved therein an organic polymer, such as up to l0 percent by weight of poly( methylmethacrylate) or poly(a-alkyl cyanoacrylate) or up to 25 percent by weight of liquid unsaturated polyester, and filler. Exemplary composi- When formulation B is employed on painted surfaces submerged in sea water, bond strengths of from 100 to I25 pounds per square inch are obtained, [The abbreviation pt." is usedfor parts by weight.]

The pastes of this invention are applied to a surface submerged in water as, e.g., a glob. (Said pastes are equally effec tive in fresh water and in sea water.) The other surface to be adhered is then pressed over the glob against the first surface and held there for a period of up to 5 minutes.

To deliver the paste to the surface to which it is to be applied, it is preferably placed in a tube and squeezed through a nozzle or throat onto said surface.

Tests were conducted with compositions of this invention wherein a) a second surface is immediately pressed against a first surface to which paste has been applied, b) a second sur face is pressed against a first surface one minute after a glob of paste has been placed on the first surface, and c) a second surface is presscd against a first surface 2 minutes after a glob of paste has been placed on the first surface, all surfaces being submerged in water. The strength of the resulting bonds was then tested. All bond tension tests were carried out with a Baldwin Universal Testing Machine at ajaw separation speed of0.05 inch per minute.

In the examples which follow, a paste is made by adding the stated filler to the specified liquid ot-cyanoacrylate. When a plurality of fillers are used, they can be admixed with the acyanoacrylate sequentially in any order or as an admixture. in the actual examples, the amorphous silica is added last. Alternatively, the monomer can be added to the filler. The acyanoacrylate is prepared according to the method of Jeremias (U.S. Pat. No. 2,763,677) and contains an acidic in hibitor against anionic polymerization. The pH designated for said a-cyanoacrylate (containing the acidic inhibitor) is the pH obtained by mixing 1 gram of the a-cyanoacrylate and 0.2 gram of sodium chloride in 50 milliliters of distilled water. Said pH is 3.7 except for example 19, where it is 3.0; example 24, where it is 2.7; and example 39, where it is 4.15.

The paste formed from the admixture of filler with the acyanoacrylate (monomer) is stirred until smooth and then placed in a squeeze tube from which it is spread, under water, on one of the two surfaces to be adhered. The other of said two surfaces is then pressed for from 2 to 3 minutes against the paste on said one surface.

Monomer Average Bond ar-cyant Filler Paste Strength in Example acrylate gramsFlow Surfaces" Tension 1 octyl CaCO 3.4 201 1 l0 SiO 0.3 fair 187' 2 heptyl CaCO 2.7 excellent 100" 175' 3' heptyl CrtCO 2.6 475 SiO 0.1 to 410' 0.2 4 hcptyl CaCO, 3.4 609 710 S hcplyl CaCO 2.7 rubber/steel 74' rubber/wood 31' glass/glass e hexyl caco, 2.5 good 225" 135 112 7 amyl CaCO 3.5 fair 253 80 150 8 butyl CaCO 2.0 very thin 420 and fluid 9 many! CaCO 2.7 210 SiO, 0.05 10 dccyl CaCO 2.7 200 SiO 0.05 11 cyclohexyl CaCtZ) 2.7 885 SiO, 0.05 12 cthoxy- CaCQ 2.7 270 ethyl SiO, 0.1 13 isobutyl CaCO 2.7 g 260 SiO, 0.05 14 isopropyl CaCO 2.7 360 SiO, 0.05 15 2-cthyl- CaCO 2.7 310 hexyl SiO, 0.05 16 propyl" CaCO 2.6 200 SiO, 041 17 ethyl" CaCO 2.7 75

SiO 0.1 18 methyl CaCO 2.7 75

SiO, 0.1 19 hcxyl BaCO, 2.7 750 SiO 0.1 20 2-cthyl- CaSO 21-1 0 20 210 hexyl SiO, 0.1 21 butyl CaSO. AH,0 3.0 80

SiO 0.1 22 allyl CaC0 2.7 250 SiO, 0.l n-hcxyland BaCO 2.7 400 n-amyl SiO 0.1 24 trifluoro- CaCO 2.7 155 isopropyl sio, o.|

All examples adhere two stainless steel surfaces under fresh water. unless otherwise specified.

*Salt water used in this sample.

Immediate sealing.

" Sealing aftera l-minute immersion.

Sealing after a 2-minute immersion.

Glass slides broke. precluding reading.

' Bond strengths as high as 580 p.s.i. obtained in individual tests.

! Peel strength; rubber peeled from steel and wood substrates.

' Held together for only 1 minute under water.

Paste delivered as a glob through a polyethylene tube to one of the two steel surfaces held under waterv All silica (S10 used in the examples in conjunction with the filler is amorphous silica.

1 in each example 3.0 grams of monomer are used, except in Example 1 where 6.1 grams of monomer are used; in Example 23, 1.5 grams of each monomer are P a l s lu 529K9 ea s.slhsw tsspssifiat.

Heptyl-a-cyanoacrylate admixed with calcium carbonate (CaCO and amorphous silica (as in the examples) was also found to form strong bonds (under water) of aluminum to aluminum. in the same manner wood/wood and rubber/rubber bonds were formed. Although there may be some variation in maximum tensile or shear strengths and the optimum pH may differ, strong bonds are likewise formed under water for glass/glass, plastic/plastic (phenol/formaldehyde thermoset plastic) and combinations of the noted substrates, e.g. st ol/aluminum nlngtivlrvlass fittrl woodlnainted'steel.

hexyl-a-cyanoarcylate (pH 3.7), 3.6 parts by weight of calcium carbonate and 0.2 part by weight of Cab-O-Sil, additional bonds are prepared under water as set forth in examples 25 to 32. in these examples all test specimens (except those with corroded or painted surfaces) are prepared for adhesive bonding by vapor dcgrcasing for 5 minutes with trichloroethylene. This is followed by a hot water rinse and then a final wash in methyl ethyl kctonc.

The procedure for each test (run) in examples 25 to 32 is as follows:

a. Water in a container is regulated at the indicated temperature;

b. Test specimens are submerged in the water;

c. Adhesive is applied to bonding surface of one submerged test specimen;

(1. Adhesive is spread over entire bonding area by sliding test specimens over one another;

e. Moderate hand pressure (approximately 1 pound) is applied between bonding surfaces for a time interval A;

f. Bonded test specimens removed from water and placed in Dillon Dynamometer for pull tests;

g. Load applied between test specimens; time interval B is the interval between conclusion of time interval A and application of load.

The adhesive cure begins immediately upon contact with water. Up to 2 minutes are available following application to spread the adhesive and bring the bonding surfaces together.

All ingredients are stored in closed containers. The hcxyl-acyanoacrylate is packaged in a polyethylene bottle. Cardboard cans are used to package the amorphous silica and the calcium carbonate.

The mixed adhesive paste can be readily applied from its collapsible squeeze tube container for a period up to 4 hours.

The following portions of Federal Test Standard 175, Adhesive Methods of Testing, are used for performing the physical tests:

Method 101 1.1 Tensile Properties of Adhesives Method 1033. lT Shear Strength Properties of Adhesives by Tensile Loading.

All tests for each example are performed on the same day with the same adhesive batch. The bond area for each test is one square inch. 7.8 grams of mixed adhesive composition is adequate for approximately 20 thin film tests.

The aluminum alloy employed in each of examples 25 through 32 is aluminum alloy AA6061T6 anodized per Mil-A-625 and having a surface roughness of In each of said examples the steel is steel per MilS-l62l6, Grade HY-; in examples 25, 28, 29, 31 and 32 the surface roughness is in examples 26 and 30 the surface bonded is badly oxidized to a finish of approximately in example 27 the surface bonded is painted per NAVORD USTD 52, System No. 48 (antifouling).

EXAMPLE 25 Steel is adhered to anodized aluminum alloy submerged in a 3 percent solution of salt (NaCl) water having a temperature of 70 F. Ten repetitions produce the following results:

' Tim! in u-mmlm nrimarc seccimcn bond A Time in seconds unless otherwise EXAMPLE 26 Badly oxidized steel is adhered to anodized aluminum alloy submerged in tap water having a temperature of 70 F. [In this example and in examples 27 through 32 A and B have the same meanings as indicated in the respective footnotes in Example 25.] Five tests yield the following results:

Painted steel is adhered to anodized aluminum alloy submerged in tap water having a temperature of 70 F. in each of five tests A is 45 seconds and B is 105 seconds; the respective tensile strengths are 240 p.s.i., 225 p.s.i., 230 p.s.i., 265 p.s.i. and 320 p.s.i. An average tensile strength of 256 pounds per square inch is thus obtained.

EXAMPLE 28 Steel is adhered to anodized aluminum alloy submerged in tap water having a temperature of 70 F. In each of tests A is 45 seconds. Other data follow:

8 Tensile Strength (p.s.i.)

a Bl 400 b 109 740 e 44 620 f 54 am g 104 525 h 75 680 i 76 (iii) j 47 625 Average 562 EXAMPLE 29 ln examples 29 to 32 shear specimens are prepared from rectangular slides having an overlapping bond area of 1 inch. Adhesive paste of the same composition as that employed for examples to 28 is applied to the slides in the same manner as it is applied to the substrates therein indicated. The details of example 29 are the same as those of example 28 except as otherwise specified. In each of 10 tests A is 45 seconds and B is 105 seconds. The respective shear strengths in pounds per square inch are: 500, 260, 345, 365, 410, 415, 230, 280, 320 and 440, the average of which is 361 p.s.i.

EXAMPLE 30 Badly oxidized steel is adhered to anodized aluminum alloy submerged in tap water having a temperature of 70 F. In each of 10 runs A is 45 seconds and B is 105 seconds. The respective shear strengths in pounds per square inch are: 405, 415, 430, 475, 405, 460, 465, 425, 400 and 410, the average of which is 429 p.s.i.

EXAMPLE 31 Steel having a surface roughness of is adhered to anodized aluminum alloy submerged in tap water having a temperature of 32 F. In each of 10 runs A is 45 seconds and is 105 seconds. The respective shear strengths in pounds per square inch are: 355, 275, 395, 270, 350, 445, 340, 430, 135 and 430, the average of which is 342 p.s.i.

EXAMPLE 32 Steel is adhered to anodized aluminum alloy submerged in tap water having a temperature of 70 F. For these tests the thickness of the adhesive layer between the two substrates is 0.062 inch. in each of three runs A is seconds and B is 60 minutes. The respective shear strengths in pounds per square inch are: 65, l 10 and 75, the average of which is 83 p.s.i.

EXAMPLE 33 TO 38 Example Substrates Tensile Strength 33 wood to wood (maple) 300 370 34 plastic to plastic (phenolic)250 270 35 rubber stopper to wood (maple) 31 36 rubber to steel 74 37 painted steel to painted stccl 680 38 aluminum to aluminum 340 note: "l'hc result is actually that for a peel test since the rubber stretches and peels from the substrate to which it is adhered.

EXAMPLE 4 Following the same procedure as that employed for examples l to 24 and using paste prepared from 3.0 g. of hexyl acyanoacrylate and 1.0 g. of decolorizing charcoal (Atlas Chemical Co., Wilmington, Delaware), bonds made under tap water in less than one minute between standard A.S.T.M. 1 inch-square stainless steel jigs displayed tensile strengths of p.s.i.

Compositions of this invention have a pastelike consistency and are capable of a) being applied to a substrate submerged in water, b) adhering together two substances submerged in water and c) achieving a bond strength between the two substrates of at least 100 pounds per square inch in less than 1 hour.

To one versed in the adhesive art, it is exceedingly surprising that strong adhesive bonds can be achieved under water. it is also surprising, knowing the properties of methyl-ozcyanoacrylate, that this family of anionically initiated monomers may be utilized at all under water at neutral or alkaline pH. It had generally been accepted that the methyl ester was too reactive in water. The longer chain esters, however, permit more working time for the preparation of good adhesive joints.

The invention and its advantages are readily understandable from the foregoing description. It is apparent that various changes may be made in the processes and compositions without departing from the spirit and scope of the invention or sacrificing its material advantages, the processes and compositions hereinbefore described being merely illustrative of preferred embodiments of the invention.

We claim:

1. A process of adhering two solid surfaces under water which comprises a) applying to one of the two surfaces submerged in water a thick section of a composition having a pastelike consistency and containing, as essential ingredients,

1. 2 to 4 parts by weight of at least one B-unsubstituted acyanoacrylic acid ester of the formula H C=C(CN)- CO-OR which is liquid at room temperature and atmospheric pressure wherein R is a member selected from the group consisting of alkyl having from 1 to 10 carbon atoms; alkoxyalkyl having from 1 to carbon atoms, the alkoxy having from 1 to 4 carbon atoms; cyclohexyl; phenyl and allyl,

. 2 to 4 parts by weight of water-insoluble solid filler which is essentially inert with respect to the a-cyanoacrylic acid ester and insoluble therein, where said filler comprises at least one member selected from the group consisting of calcium carbonate, calcium sulfate dihydrate, calcium oxide, calcium sulfate, titanium dioxide, zinc oxide, zinc hydroxide, magnesium oxide, stannic oxide, stannous oxide, aluminum oxide, aluminum silicate, calcium silicate,

53 UNITED STATES PATENT OFFICE CERTIFICATE OF CORRECTION Patent No. 3,607,542 Dated September 21, 1971 Inventor) Fred Leonard and George Brandes It is certified that error appears in the above-identified patent and that said Letters Patent are hereby corrected as shown below:

[- Column 1 line 1, after the title "UNDERWATER ADHESIVE PROCESS",

add the following paragraph:

-The invention described herein may be manufactured and used by or for the Government for governmental purposes without the payment to us of any royalty thereon.--

Column 3, line 40, the comma should be a period line 63, the word "pas tlike" should read --pastelike--.

Column 6, line 1, before "hexyl-" should be inserted -Employing a paste prepared from 4.0 parts by weight of"; same line, "cganoarcylate" should read --cyanoacry1ate--; line 46, 2 should read line 49, should read g line 50, should read k line 76, after "otherwise" insert --specified) from bond preparation to the application of load in testing.--

Column 7, line 70, should read Column 8, line 35, "EXAMPLE 4" should read --EXAMPLE 39--; line 71 "1. should read --l) Column 9, line 4, "2." (first occurrence) should read -2)--.

Column 10, line 6, "3." should read --3) Signed and sealed this 21 st day of March 1 972.

(SEAL) Attest:

LEDWARD M.FLETCHER,JR ROBERT GOTTSCHALK J Attesting Officer Commissioner of Patents 

2. 2 to 4 parts by weight of water-insoluble solid filler which is essentially inert with respect to the Alpha -cyanoacrylic acid ester and insoluble therein, where said filler comprises at least one member selected from the group consisting of calcium carbonate, calcium sulfate dihydrate, calcium oxide, calcium sulfate, titanium dioxide, zinc oxide, zinc hydroxide, magnesium oxide, stannic oxide, stannous oxide, aluminum oxide, aluminum silicate, calcium silicate, zinc silicate, calcium aluminate, mercuric oxide, silver oxide, cuprous oxide, cupric oxide, strontium oxide, ferrous oxide, ferric oxide, zinc phosphate, calcium phosphate, aluminum phosphate, talc, barium sulfate, barium carbonate and calcium sulfate hemihydrate, and
 3. from 0 to 0.3 parts by weight of finely divided silica, b. pressing the second of said two surfaces over the composition and against the surface to which said composition was applied and c. holding said two surfaces in contact with said composition until said composition sets. 